AnnotationViews

Question

我试图通过CGAffineTransformMakeRotation根据方向调整某些注释视图的旋转。 然而，我对此函数的测试给出了奇怪的结果：如果我应用M_PI/2的旋转，如代码中的示例，它略微向下指向，如果我使用M_PI它指向一直向下，在M_PI/4，它指向左侧的底部。如何计算旋转而不是以弧度为单位指向输入角度？这是我使用的代码块：

BOOL oldVerticalInverted=NO;
#define degreesToRadians(x) (M_PI * x / 180.0)
#define radiandsToDegrees(x) (x * 180.0 / M_PI)

-(void)adjustAnnotationFor:(CLLocationCoordinate2D)start ToCoordinates:(CLLocationCoordinate2D)end completion:(void (^)(void))completion{
 float newCoordinatesAngle=[Line angleFromCoordinate:start toCoordinate:end];
 float newAngle=newCoordinatesAngle-M_PI/4;
 float angle2Rotate=newAngle-self.angle;
 angle2Rotate=M_PI; //testing
 NSLog(@"oldAngle=%f newAngle=%f angle to rotate=%f %@",   radiandsToDegrees(self.angle), radiandsToDegrees(newAngle), radiandsToDegrees(angle2Rotate), cos(self.angle)<0?@"inverted": @"straight");
 self.angle=newAngle;

 NSLog(@"setting angle to %f cos=%f", self.angle, cos(self.angle));
 if (view!=nil){
    dispatch_async(dispatch_get_main_queue(), ^{
        [UIView animateWithDuration:.5 animations:^{
            BOOL verticallyInverted=cos(self.angle)<0;
            int invertVertical=oldVerticalInverted==verticallyInverted?1:-1;
            oldVerticalInverted=verticallyInverted;
            CGAffineTransform affineInvert=CGAffineTransformMakeScale(1, invertVertical);
            CGAffineTransform rotateAffine=CGAffineTransformMakeRotation(angle2Rotate);
            view.transform=CGAffineTransformConcat(rotateAffine, affineInvert);
        }
                        completion :^(BOOL finished){
                            if (completion) completion();
                        }];
    });
 }

}

Answer 1

事实上，由于我忽略的原因，足以在动画中为注释视图指定适当旋转的角度：这是更新的代码，包括用于在向左指向时反转注释的块：     BOOL oldVerticalInverted = NO;     #define degreesToRadians（x）（M_PI * x / 180.0）     #define radiandsToDegrees（x）（x * 180.0 / M_PI）

-(void)adjustAnnotationFor:(CLLocationCoordinate2D)start ToCoordinates:(CLLocationCoordinate2D)end completion:(void (^)(void))completion{
    __block float newAngle=[Line angleFromCoordinate:start toCoordinate:end];
    __block float angle2Rotate=self.angle;
    __block BusAnnotation* blockSelf=self;
    __block BOOL blockOldInverted=oldVerticalInverted;
   NSLog(@"setto angle a %f cos=%f", self.angle, cos(self.angle));
   if (view!=nil){
    dispatch_async(dispatch_get_main_queue(), ^{
        [UIView animateWithDuration:1 animations:^{
            blockSelf.angle=newAngle;
            BOOL verticallyInverted=cos(blockSelf.angle)<0;
            int invertVertical=blockOldInverted==verticallyInverted?1:-1;
            blockOldInverted=verticallyInverted;
            CGAffineTransform affineInvert=CGAffineTransformMakeScale(1, invertVertical);
            view.transform=CGAffineTransformConcat(CGAffineTransformIdentity, affineInvert);

         }
                        completion :^(BOOL finished){
                            if (completion) completion();
                        }];
     });
 }
}

唯一剩下的问题是如何反转我在annotationView中烧毁的文本，当指向左边时会反转：这就是我如何制作后一部分：

-(UIImage *)burnText:(NSString *)text ofBackColor:(UIColor*)color intoImage:(UIImage *)img inRect:(CGRect)aRect font:(UIFont*) font{

    UIGraphicsBeginImageContextWithOptions(img.size,NO,0.0);

    CGRect aRectangle = CGRectMake(0,0, img.size.width, img.size.height);
    [img drawInRect:aRectangle];
    NSMutableParagraphStyle *textStyle = [[NSMutableParagraphStyle defaultParagraphStyle] mutableCopy];
    textStyle.lineBreakMode = NSLineBreakByTruncatingTail;
    textStyle.alignment=NSTextAlignmentCenter;

    NSDictionary *dictionary = @{ NSFontAttributeName: font,
                              NSParagraphStyleAttributeName: textStyle,
                              NSForegroundColorAttributeName: [UIColor blackColor],
                              NSBackgroundColorAttributeName: color};
    [text drawInRect:aRect withAttributes:dictionary];
    UIImage *theImage=UIGraphicsGetImageFromCurrentImageContext();   // extract the image
    UIGraphicsEndImageContext();     // clean  up the context.
    theImage.accessibilityValue=text;
    return theImage;
}